carboxysome

Carboxysomes are proteinaceous organelles found in certain anaerobic microorganisms, such as methanogens and acetogens, that facilitate the concentration of carbon dioxide (CO2) within the cell. They are composed of a protein shell that encloses a central cavity, which serves as a reservoir for CO2. This structure is crucial for the efficient fixation of CO2 into organic compounds, a process that is essential for the growth and metabolism of these microorganisms.

The formation of carboxysomes involves the self-assembly of specific proteins, which are encoded by genes that are often clustered together in the genome. The protein shell of the carboxysome is highly porous, allowing CO2 to diffuse into the central cavity while excluding other molecules. This selective permeability ensures that the CO2 concentration within the carboxysome is significantly higher than in the surrounding environment, thereby facilitating the enzymatic reactions that convert CO2 into organic compounds.

Carboxysomes are not only important for the metabolic processes of their host organisms but also have potential applications in biotechnology. For example, they can be used to enhance the efficiency of CO2 fixation in engineered microorganisms for the production of biofuels or other valuable chemicals. Additionally, the study of carboxysomes provides insights into the evolution of metabolic pathways and the adaptation of microorganisms to anaerobic environments.